Labour’s chief whip, Rosie Winterton, and its London mayoral candidate, Sadiq Khan, have been labelled as “hostile” in a leaked document that appears to rank the party’s MPs by their loyalty to the leader, Jeremy Corbyn.

Members of parliament have been separated into five different sections ranging from a “core group” of loyalists, through “neutral but not hostile”, to a final “hostile” list that includes those believed to be most negative about the current leadership.

The document underlines unrest within the shadow cabinet with a number of frontbench MPs listed in the fourth “core negative group” including Lucy Powell at education and Maria Eagle, who was moved from her role in defence to culture.

They have been placed alongside Dan Jarvis – who is seen as a potential leadership candidate if MPs try to trigger a coup against Corbyn.

A spokesman for Corbyn categorically denied a claim by the Times, which was leaked the list, that it was drawn up by Katy Clark, Corbyn’s political secretary. They also pointed out that the list included Harry Harpham, who died of cancer last month and the late veteran MP Michael Meacher who died in October. He is listed in the core group with “RIP” before his name.

Some backbenchers speculated that the hand of Damian McBride, the combative spin doctor to Gordon Brown who recently joined the team of the shadow defence secretary, Emily Thornberry, may have been behind the release of the list. The suggestion is categorically denied by McBride.

“I don’t know why the shadow leader of the House [Chris Bryant] is shouting at me,” he said. “We’ve got a very interesting document today, we’ve got the spreadsheet of which Labour MP is on which side. You are shouting, but it says here you are ‘neutral but not hostile’.

“The chief whip [Rosie Winterton] on the other hand, the chief whip is being a bit quiet. There are five categories - we’ve got ‘core support’, I think you can include me in that lot, we’ve got ‘core plus’, the chief whip is being a bit quiet because she’s in ‘hostile’.”

Corbyn accused the government of being in disarray over the budget and told Conservative MPs they have “no idea” what it is like to be poor.

Labour insiders believe the list emerged from a team of MPs loyal to Corbyn, who call themselves the “core group”, and meet regularly – separately from the shadow cabinet – to discuss policy issues, and strategies for dealing with the divided state of the parliamentary party and shoring up the leader.

MPs on the list said they believed it was “kosher”. Others named alongside Khan and Winterton in the most hostile group are Margaret Hodge, Pat McFadden and Rachel Reeves.

While the most loyal includes the shadow chancellor, John McDonnell, the shadow energy minister, Clive Lewis, the shadow minister for women, Cat Smith, and the shadow international development secretary, Diane Abbott.

When asked if Sadiq Khan was hostile towards Corbyn, a spokesman for the mayoral candidate said: “No. Sadiq Khan is his own person and is fighting his own campaign to be mayor of London. Jeremy Corbyn’s name is not on the ballot paper.”

John Woodcock, who is on the hostile list, said: “It’s sad that the public calls for unity and a new politics seems to be a front for this sort of internal attack operation, which harks back to the bad old days.”

Chuka Umunna, also listed as hostile, said: “I was never offered a job on the front bench by Jeremy but have been strongly opposing the Tory government from the backbenches. I have always voted with the Labour whip. I am heading a review, warmly supported by Jeremy, into the party’s support in our different ethnic minority communities. I am also leading efforts in the House of Commons to put tackling serious youth violence back on the national agenda, which I have discussed with Jeremy because it impacts on both our constituencies.

“My concern is that a divisive list of this kind does nothing to help us take on the Tories and get back into Government or tackle the real issues adversely affecting constituencies like mine.”

Alison McGovern, who is on the hostile list, tweeted: “Only folks I’m hostile towards is incompetent Tories,” adding a link to a New Statesman piece about the former work and pensions secretary, Iain Duncan Smith.

The release of the list comes as a number of backbenchers have been making high-profile interventions against the Conservatives in a bid to try to show Labour members that they are still active within the party. One group – dubbed the “G10” – have been described as a “shadow shadow” operation.

The list has irritated MPs who are not close to Corbyn. One said on Tuesday: “A rumour of this list’s existence was circulating the Labour lobby during budget votes tonight and lots of people were pretty outraged, especially just as everyone thankfully and rightly was focusing on the Tories during a moment of chaos for them.”